Study On The Application Of Ultrasonic In Salting Processing Of Salted Duck

Salted duck is a famous special local product of Nanjing, and has long history. But its traditional processing has many disadvantages. In this study, the ultrasonic was used to improve the salting and cooking process; and the effects on the quality, storage properties and the volatile compounds of salted duck were studied by contrasting some indexes of the salted ducks processed by traditional processing and the ultrasonic processing. The detailed results are as follows,1. Ultrasonic wave was used in this study to improve the salting processing of salted duck. The optimal conditions were determined by single factor and orthogonal experiments. The results indicated that the optimum conditions were as follows: Ultrasonic frequency was 26.4 kHz, ultrasonic power was 400W, salting concentration was 12%, salting period for 80 min. Meanwhile the comparison of the qualities of salted ducks salted by ultrasonic technique and the traditional method were also studied to discuss the effect of ultrasonic salting process on the quality of salted duck. The results indicated that the ultrasonic can promote the diffusion and osmosis of salt and flavor compounds towards meat effectively, and the tenderness of meat was also improved, the L* value of meat color was increased and a* value was decreased significantly while b* values was no difference. The content of free amino acids was significantly increased; the digestibility of duck meat extraction with trypsin was significantly increased; the processing period was significantly decreased while maintained the unique quality of the traditional salt duck that have light color and taste and high tenderness.2. The feasibility of cooking meat method assistant with ultrasonic was discussed in this paper. The salted duck as experiment material was studied. The results showed that the ultrasonic technique was applicable to cook meat. Cooking meat assistant with ultrasonic was faster than traditional method. Ultrasonic treatment also made the meat acquire higher tenderness and lower cooking losses ,and more palatable for the ultrasonic can promote the diffusion and osmosis of flavor compounds of spices towards meat effectively, and the new cooking method required less cooking energy than the traditional method.3. The storage properties of salted duck were studied by contrasting some indexes of the salted ducks processed by traditional process and the ultrasonic process. The total bacterial count, color values, tenderness, the acid values, the peroxide values and TBARS during storage period were analyzed. The results showed that the physical, chemical and microbial indexes of the salted duck processed by ultrasonic process were steady. Compared with the traditional one, the total bacterial count and the shear force values of the ultrasonic processing product were decreased, and the L* values of color increased largely, a* values decreased significantly, and the b* values increased significantly. The indexes of oxidative stability indicated that the level of the ultrasonic processing product was significantly higher than the traditional one at the initial storage stage, then kept increasing stably, but was no significantly difference at the late stage of storage.4. The volatile compounds extracted with solid-phase microextraction method from salted ducks produced using ultrasonic and traditional processing were analyzed by GC-MS. 94 volatile compounds included aldehydes, alcohols, kentons, hydrocarbons, acids, Esters, sulfur-containing compounds and N-O-containing compounds were identified. There 60 volatile compounds were identified in salted duck meat produced by traditional method and 62 in the one produced by ultrasonic method. The content of aldehydes and kentons in the sample of ultrasonic processing were higher than the traditional one and alcohols and Esters were lower, while the other volatile compounds have no difference in the two samples.